﻿
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;

// This file contains general utilities to aid in development.
// Classes here generally shouldn't be exposed publicly since
// they're not particular to any library functionality.
// Because the classes here are internal, it's likely this file
// might be included in multiple assemblies.
namespace Standard
{
    internal static partial class Utility
    {
        private static readonly Version _osVersion = Environment.OSVersion.Version;
        private static readonly Version _presentationFrameworkVersion = Assembly.GetAssembly(typeof(Window)).GetName().Version;

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        private static bool _MemCmp(IntPtr left, IntPtr right, long cb)
        {
            int offset = 0;
            for (; offset < cb - sizeof(Int64); offset += sizeof(Int64))
            {
                long left64 = Marshal.ReadInt64(left, offset);
                long right64 = Marshal.ReadInt64(right, offset);
                if (left64 != right64) return false;
            }

            for (; offset < cb; offset += sizeof(byte))
            {
                byte left8 = Marshal.ReadByte(left, offset);
                byte right8 = Marshal.ReadByte(right, offset);
                if (left8 != right8) return false;
            }

            return true;
        }

        /// <summary>The native RGB macro.</summary>
        /// <param name="c"></param>
        /// <returns></returns>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static int RGB(Color c) => c.R | (c.G << 8) | (c.B << 16);

        /// <summary>Convert a native integer that represent a color with an alpha channel into a Color struct.</summary>
        /// <param name="color">The integer that represents the color.  Its bits are of the format 0xAARRGGBB.</param>
        /// <returns>A Color representation of the parameter.</returns>
        public static Color ColorFromArgbDword(uint color) => Color.FromArgb((byte)((color & 0xFF000000) >> 24), (byte)((color & 0x00FF0000) >> 16), (byte)((color & 0x0000FF00) >> 8), (byte)((color & 0x000000FF) >> 0));

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static int GET_X_LPARAM(IntPtr lParam) => LOWORD(lParam.ToInt32());

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static int GET_Y_LPARAM(IntPtr lParam) => HIWORD(lParam.ToInt32());

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static int HIWORD(int i) => (short)(i >> 16);

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static int LOWORD(int i) => (short)(i & 0xFFFF);

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        [SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")]
        public static bool AreStreamsEqual(Stream left, Stream right)
        {
            if (left == null) return right == null;
            if (right == null) return false;
            if (!left.CanRead || !right.CanRead) throw new NotSupportedException("The streams can't be read for comparison");
            if (left.Length != right.Length) return false;

            int length = (int)left.Length;

            // seek to beginning
            left.Position = 0;
            right.Position = 0;

            // total bytes read
            int totalReadLeft = 0;
            int totalReadRight = 0;

            // bytes read on this iteration
            int cbReadLeft = 0;
            int cbReadRight = 0;

            // where to store the read data
            byte[] leftBuffer = new byte[512];
            byte[] rightBuffer = new byte[512];

            // pin the left buffer
            GCHandle handleLeft = GCHandle.Alloc(leftBuffer, GCHandleType.Pinned);
            IntPtr ptrLeft = handleLeft.AddrOfPinnedObject();

            // pin the right buffer
            GCHandle handleRight = GCHandle.Alloc(rightBuffer, GCHandleType.Pinned);
            IntPtr ptrRight = handleRight.AddrOfPinnedObject();

            try
            {
                while (totalReadLeft < length)
                {
                    Assert.AreEqual(totalReadLeft, totalReadRight);
                    cbReadLeft = left.Read(leftBuffer, 0, leftBuffer.Length);
                    cbReadRight = right.Read(rightBuffer, 0, rightBuffer.Length);
                    // verify the contents are an exact match
                    if (cbReadLeft != cbReadRight) return false;
                    if (!_MemCmp(ptrLeft, ptrRight, cbReadLeft)) return false;
                    totalReadLeft += cbReadLeft;
                    totalReadRight += cbReadRight;
                }
                Assert.AreEqual(cbReadLeft, cbReadRight);
                Assert.AreEqual(totalReadLeft, totalReadRight);
                Assert.AreEqual(length, totalReadLeft);
                return true;
            }
            finally
            {
                handleLeft.Free();
                handleRight.Free();
            }
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool GuidTryParse(string guidString, out Guid guid)
        {
            Verify.IsNeitherNullNorEmpty(guidString, nameof(guidString));
            try
            {
                guid = new Guid(guidString);
                return true;
            }
            catch (FormatException)
            {
            }
            catch (OverflowException)
            {
            }
            // Doesn't seem to be a valid guid.
            guid = default(Guid);
            return false;
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsFlagSet(int value, int mask) => (value & mask) != 0;

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsFlagSet(uint value, uint mask) => (value & mask) != 0;

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsFlagSet(long value, long mask) => (value & mask) != 0;

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsFlagSet(ulong value, ulong mask) => (value & mask) != 0;

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsOSVistaOrNewer => _osVersion >= new Version(6, 0);

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsOSWindows7OrNewer => _osVersion >= new Version(6, 1);

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool IsOSWindows8OrNewer => _osVersion >= new Version(6, 2);

        /// <summary>
        /// Is this using WPF4?
        /// </summary>
        /// <remarks>
        /// There are a few specific bugs in Window in 3.5SP1 and below that require workarounds
        /// when handling WM_NCCALCSIZE on the HWND.
        /// </remarks>
        public static bool IsPresentationFrameworkVersionLessThan4 => _presentationFrameworkVersion < new Version(4, 0);

        // Caller is responsible for destroying the HICON
        // Caller is responsible to ensure that GDI+ has been initialized.
        [SuppressMessage("Microsoft.Usage", "CA2202:Do not dispose objects multiple times")]
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static IntPtr GenerateHICON(ImageSource image, Size dimensions)
        {
            if (image == null) return IntPtr.Zero;

            // If we're getting this from a ".ico" resource, then it comes through as a BitmapFrame.
            // We can use leverage this as a shortcut to get the right 16x16 representation
            // because DrawImage doesn't do that for us.
            if (image is BitmapFrame bf)
                bf = GetBestMatch(bf.Decoder.Frames, (int)dimensions.Width, (int)dimensions.Height);
            else
            {
                // Constrain the dimensions based on the aspect ratio.
                Rect drawingDimensions = new Rect(0, 0, dimensions.Width, dimensions.Height);
                // There's no reason to assume that the requested image dimensions are square.
                double renderRatio = dimensions.Width / dimensions.Height;
                double aspectRatio = image.Width / image.Height;
                // If it's smaller than the requested size, then place it in the middle and pad the image.
                if (image.Width <= dimensions.Width && image.Height <= dimensions.Height)
                    drawingDimensions = new Rect((dimensions.Width - image.Width) / 2, (dimensions.Height - image.Height) / 2, image.Width, image.Height);
                else if (renderRatio > aspectRatio)
                {
                    double scaledRenderWidth = image.Width / image.Height * dimensions.Width;
                    drawingDimensions = new Rect((dimensions.Width - scaledRenderWidth) / 2, 0, scaledRenderWidth, dimensions.Height);
                }
                else if (renderRatio < aspectRatio)
                {
                    double scaledRenderHeight = image.Height / image.Width * dimensions.Height;
                    drawingDimensions = new Rect(0, (dimensions.Height - scaledRenderHeight) / 2, dimensions.Width, scaledRenderHeight);
                }

                DrawingVisual dv = new DrawingVisual();
                DrawingContext dc = dv.RenderOpen();
                dc.DrawImage(image, drawingDimensions);
                dc.Close();

                RenderTargetBitmap bmp = new RenderTargetBitmap((int)dimensions.Width, (int)dimensions.Height, 96, 96, PixelFormats.Pbgra32);
                bmp.Render(dv);
                bf = BitmapFrame.Create(bmp);
            }

            // Using GDI+ to convert to an HICON.
            // I'd rather not duplicate their code.
            using (MemoryStream memstm = new MemoryStream())
            {
                BitmapEncoder enc = new PngBitmapEncoder();
                enc.Frames.Add(bf);
                enc.Save(memstm);
                using (ManagedIStream istm = new ManagedIStream(memstm))
                {
                    // We are not bubbling out GDI+ errors when creating the native image fails.
                    IntPtr bitmap = IntPtr.Zero;
                    try
                    {
                        Status gpStatus = NativeMethods.GdipCreateBitmapFromStream(istm, out bitmap);
                        if (Status.Ok != gpStatus) return IntPtr.Zero;
                        gpStatus = NativeMethods.GdipCreateHICONFromBitmap(bitmap, out IntPtr hicon);
                        return Status.Ok != gpStatus ? IntPtr.Zero : hicon;
                        // Caller is responsible for freeing this.
                    }
                    finally
                    {
                        Utility.SafeDisposeImage(ref bitmap);
                    }
                }
            }
        }

        public static BitmapFrame GetBestMatch(IList<BitmapFrame> frames, int width, int height) => _GetBestMatch(frames, _GetBitDepth(), width, height);

        private static int _MatchImage(BitmapFrame frame, int bitDepth, int width, int height, int bpp)
        {
            return (2 * _WeightedAbs(bpp, bitDepth, false)) +
                            _WeightedAbs(frame.PixelWidth, width, true) +
                            _WeightedAbs(frame.PixelHeight, height, true);
        }

        private static int _WeightedAbs(int valueHave, int valueWant, bool fPunish)
        {
            int diff = valueHave - valueWant;
            return diff >= 0 ? diff : (fPunish ? -2 : -1) * diff;
        }

        /// From a list of BitmapFrames find the one that best matches the requested dimensions.
        /// The methods used here are copied from Win32 sources.  We want to be consistent with
        /// system behaviors.
        private static BitmapFrame _GetBestMatch(IList<BitmapFrame> frames, int bitDepth, int width, int height)
        {
            int bestScore = int.MaxValue;
            int bestBpp = 0;
            int bestIndex = 0;
            bool isBitmapIconDecoder = frames[0].Decoder is IconBitmapDecoder;
            for (int i = 0; i < frames.Count && bestScore != 0; ++i)
            {
                int currentIconBitDepth = isBitmapIconDecoder ? frames[i].Thumbnail.Format.BitsPerPixel : frames[i].Format.BitsPerPixel;
                if (currentIconBitDepth == 0) currentIconBitDepth = 8;
                int score = _MatchImage(frames[i], bitDepth, width, height, currentIconBitDepth);
                if (score < bestScore)
                {
                    bestIndex = i;
                    bestBpp = currentIconBitDepth;
                    bestScore = score;
                }
                else if (score == bestScore)
                {
                    // Tie breaker: choose the higher color depth.  If that fails, choose first one.
                    if (bestBpp >= currentIconBitDepth) continue;
                    bestIndex = i;
                    bestBpp = currentIconBitDepth;
                }
            }
            return frames[bestIndex];
        }

        // This can be cached.  It's not going to change under reasonable circumstances.
        private static int s_bitDepth; // = 0;

        private static int _GetBitDepth()
        {
            if (s_bitDepth != 0) return s_bitDepth;
            using (SafeDC dc = SafeDC.GetDesktop())
                s_bitDepth = NativeMethods.GetDeviceCaps(dc, DeviceCap.BITSPIXEL) * NativeMethods.GetDeviceCaps(dc, DeviceCap.PLANES);
            return s_bitDepth;
        }

        /// <summary>
        /// Simple guard against the exceptions that File.Delete throws on null and empty strings.
        /// </summary>
        /// <param name="path">The path to delete.  Unlike File.Delete, this can be null or empty.</param>
        /// <remarks>
        /// Note that File.Delete, and by extension SafeDeleteFile, does not throw an exception
        /// if the file does not exist.
        /// </remarks>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDeleteFile(string path)
        {
            if (!string.IsNullOrEmpty(path)) File.Delete(path);
        }

        /// <summary>GDI's DeleteObject</summary>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDeleteObject(ref IntPtr gdiObject)
        {
            IntPtr p = gdiObject;
            gdiObject = IntPtr.Zero;
            if (p != IntPtr.Zero) NativeMethods.DeleteObject(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDestroyIcon(ref IntPtr hicon)
        {
            IntPtr p = hicon;
            hicon = IntPtr.Zero;
            if (p != IntPtr.Zero) NativeMethods.DestroyIcon(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDestroyWindow(ref IntPtr hwnd)
        {
            IntPtr p = hwnd;
            hwnd = IntPtr.Zero;
            if (NativeMethods.IsWindow(p)) NativeMethods.DestroyWindow(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDispose<T>(ref T disposable) where T : IDisposable
        {
            // Dispose can safely be called on an object multiple times.
            IDisposable t = disposable;
            disposable = default;
            t?.Dispose();
        }

        /// <summary>GDI+'s DisposeImage</summary>
        /// <param name="gdipImage"></param>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void SafeDisposeImage(ref IntPtr gdipImage)
        {
            IntPtr p = gdipImage;
            gdipImage = IntPtr.Zero;
            if (p != IntPtr.Zero) NativeMethods.GdipDisposeImage(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        [SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")]
        public static void SafeCoTaskMemFree(ref IntPtr ptr)
        {
            IntPtr p = ptr;
            ptr = IntPtr.Zero;
            if (p != IntPtr.Zero) Marshal.FreeCoTaskMem(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        [SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")]
        public static void SafeFreeHGlobal(ref IntPtr hglobal)
        {
            IntPtr p = hglobal;
            hglobal = IntPtr.Zero;
            if (p != IntPtr.Zero) Marshal.FreeHGlobal(p);
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        [SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")]
        public static void SafeRelease<T>(ref T comObject) where T : class
        {
            T t = comObject;
            comObject = default(T);
            if (t == null) return;
            Assert.IsTrue(Marshal.IsComObject(t));
            Marshal.ReleaseComObject(t);
        }

        /// <summary>
        /// Utility to help classes concatenate their properties for implementing ToString().
        /// </summary>
        /// <param name="source">The <see cref="StringBuilder"/> to concatenate the results into.</param>
        /// <param name="propertyName">The name of the property to be concatenated.</param>
        /// <param name="value">The value of the property to be concatenated.</param>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void GeneratePropertyString(StringBuilder source, string propertyName, string value)
        {
            Assert.IsNotNull(source);
            Assert.IsFalse(string.IsNullOrEmpty(propertyName));
            if (source.Length != 0) source.Append(' ');
            source.Append(propertyName);
            source.Append(": ");
            if (string.IsNullOrEmpty(value))
                source.Append("<null>");
            else
            {
                source.Append('\"');
                source.Append(value);
                source.Append('\"');
            }
        }

        /// <summary>
        /// Generates ToString functionality for a struct.  This is an expensive way to do it,
        /// it exists for the sake of debugging while classes are in flux.
        /// Eventually this should just be removed and the classes should
        /// do this without reflection.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="object"></param>
        /// <returns></returns>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        [Obsolete]
        public static string GenerateToString<T>(T @object) where T : struct
        {
            StringBuilder sbRet = new StringBuilder();
            foreach (PropertyInfo property in typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance))
            {
                if (sbRet.Length != 0) sbRet.Append(", ");
                Assert.AreEqual(0, property.GetIndexParameters().Length);
                object value = property.GetValue(@object, null);
                string format = null == value ? "{0}: <null>" : "{0}: \"{1}\"";
                sbRet.AppendFormat(format, property.Name, value);
            }
            return sbRet.ToString();
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void CopyStream(Stream destination, Stream source)
        {
            Assert.IsNotNull(source);
            Assert.IsNotNull(destination);
            destination.Position = 0;
            // If we're copying from, say, a web stream, don't fail because of this.
            if (source.CanSeek)
            {
                source.Position = 0;
                // Consider that this could throw because
                // the source stream doesn't know it's size...
                destination.SetLength(source.Length);
            }
            byte[] buffer = new byte[4096];
            int cbRead;
            do
            {
                cbRead = source.Read(buffer, 0, buffer.Length);
                if (cbRead != 0) destination.Write(buffer, 0, cbRead);
            }
            while (buffer.Length == cbRead);

            // Reset the Seek pointer before returning.
            destination.Position = 0;
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static string HashStreamMD5(Stream stm)
        {
            stm.Position = 0;
            StringBuilder hashBuilder = new StringBuilder();
            using (MD5 md5 = MD5.Create())
            {
                foreach (byte b in md5.ComputeHash(stm)) hashBuilder.Append(b.ToString("x2", CultureInfo.InvariantCulture));
                return hashBuilder.ToString();
            }
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static void EnsureDirectory(string path)
        {
            if (!Directory.Exists(Path.GetDirectoryName(path))) Directory.CreateDirectory(Path.GetDirectoryName(path));
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static bool MemCmp(byte[] left, byte[] right, int cb)
        {
            Assert.IsNotNull(left);
            Assert.IsNotNull(right);
            Assert.IsTrue(cb <= Math.Min(left.Length, right.Length));

            // pin this buffer
            GCHandle handleLeft = GCHandle.Alloc(left, GCHandleType.Pinned);
            IntPtr ptrLeft = handleLeft.AddrOfPinnedObject();
            // pin the other buffer
            GCHandle handleRight = GCHandle.Alloc(right, GCHandleType.Pinned);
            IntPtr ptrRight = handleRight.AddrOfPinnedObject();
            bool fRet = _MemCmp(ptrLeft, ptrRight, cb);
            handleLeft.Free();
            handleRight.Free();
            return fRet;
        }

        private class _UrlDecoder
        {
            private readonly Encoding _encoding;
            private readonly char[] _charBuffer;
            private readonly byte[] _byteBuffer;
            private int _byteCount;
            private int _charCount;

            [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
            public _UrlDecoder(int size, Encoding encoding)
            {
                _encoding = encoding;
                _charBuffer = new char[size];
                _byteBuffer = new byte[size];
            }

            [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
            public void AddByte(byte b) => _byteBuffer[_byteCount++] = b;

            [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
            public void AddChar(char ch)
            {
                _FlushBytes();
                _charBuffer[_charCount++] = ch;
            }

            [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
            private void _FlushBytes()
            {
                if (_byteCount <= 0) return;
                _charCount += _encoding.GetChars(_byteBuffer, 0, _byteCount, _charBuffer, _charCount);
                _byteCount = 0;
            }

            [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
            public string GetString()
            {
                _FlushBytes();
                return _charCount > 0 ? new string(_charBuffer, 0, _charCount) : "";
            }
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static string UrlDecode(string url)
        {
            if (url == null) return null;

            _UrlDecoder decoder = new _UrlDecoder(url.Length, Encoding.UTF8);
            int length = url.Length;
            for (int i = 0; i < length; ++i)
            {
                char ch = url[i];
                if (ch == '+')
                {
                    decoder.AddByte((byte)' ');
                    continue;
                }

                if (ch == '%' && i < length - 2)
                {
                    // decode %uXXXX into a Unicode character.
                    if (url[i + 1] == 'u' && i < length - 5)
                    {
                        int a = _HexToInt(url[i + 2]);
                        int b = _HexToInt(url[i + 3]);
                        int c = _HexToInt(url[i + 4]);
                        int d = _HexToInt(url[i + 5]);
                        if (a >= 0 && b >= 0 && c >= 0 && d >= 0)
                        {
                            decoder.AddChar((char)((a << 12) | (b << 8) | (c << 4) | d));
                            i += 5;

                            continue;
                        }
                    }
                    else
                    {
                        // decode %XX into a Unicode character.
                        int a = _HexToInt(url[i + 1]);
                        int b = _HexToInt(url[i + 2]);

                        if (a >= 0 && b >= 0)
                        {
                            decoder.AddByte((byte)((a << 4) | b));
                            i += 2;

                            continue;
                        }
                    }
                }

                // Add any 7bit character as a byte.
                if ((ch & 0xFF80) == 0)
                    decoder.AddByte((byte)ch);
                else
                    decoder.AddChar(ch);
            }
            return decoder.GetString();
        }

        /// <summary>
        /// Encodes a URL string.  Duplicated functionality from System.Web.HttpUtility.UrlEncode.
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        /// <remarks>
        /// Duplicated from System.Web.HttpUtility because System.Web isn't part of the client profile.
        /// URL Encoding replaces ' ' with '+' and unsafe ASCII characters with '%XX'.
        /// Safe characters are defined in RFC2396 (http://www.ietf.org/rfc/rfc2396.txt).
        /// They are the 7-bit ASCII alphanumerics and the mark characters "-_.!~*'()".
        /// This implementation does not treat '~' as a safe character to be consistent with the System.Web version.
        /// </remarks>
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        public static string UrlEncode(string url)
        {
            if (url == null) return null;
            byte[] bytes = Encoding.UTF8.GetBytes(url);
            bool needsEncoding = false;
            int unsafeCharCount = 0;
            foreach (byte b in bytes)
            {
                if (b == ' ')
                    needsEncoding = true;
                else if (!_UrlEncodeIsSafe(b))
                {
                    ++unsafeCharCount;
                    needsEncoding = true;
                }
            }

            if (!needsEncoding) return Encoding.ASCII.GetString(bytes);
            byte[] buffer = new byte[bytes.Length + (unsafeCharCount * 2)];
            int writeIndex = 0;
            foreach (byte b in bytes)
            {
                if (_UrlEncodeIsSafe(b))
                    buffer[writeIndex++] = b;
                else if (b == ' ')
                    buffer[writeIndex++] = (byte)'+';
                else
                {
                    buffer[writeIndex++] = (byte)'%';
                    buffer[writeIndex++] = _IntToHex((b >> 4) & 0xF);
                    buffer[writeIndex++] = _IntToHex(b & 0xF);
                }
            }
            bytes = buffer;
            Assert.AreEqual(buffer.Length, writeIndex);
            return Encoding.ASCII.GetString(bytes);
        }

        // HttpUtility's UrlEncode is slightly different from the RFC.
        // RFC2396 describes unreserved characters as alphanumeric or
        // the list "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
        // The System.Web version unnecessarily escapes '~', which should be okay...
        // Keeping that same pattern here just to be consistent.
        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        private static bool _UrlEncodeIsSafe(byte b)
        {
            if (_IsAsciiAlphaNumeric(b)) return true;

            switch ((char)b)
            {
                case '-':
                case '_':
                case '.':
                case '!':
                //case '~':
                case '*':
                case '\'':
                case '(':
                case ')':
                    return true;

                default: return false;
            }
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        private static bool _IsAsciiAlphaNumeric(byte b) => (b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || (b >= '0' && b <= '9');

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        private static byte _IntToHex(int n)
        {
            Assert.BoundedInteger(0, n, 16);
            return n <= 9 ? (byte)(n + '0') : (byte)(n - 10 + 'A');
        }

        [SuppressMessage("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
        private static int _HexToInt(char h)
        {
            if (h >= '0' && h <= '9') return h - '0';
            if (h >= 'a' && h <= 'f') return h - 'a' + 10;
            if (h >= 'A' && h <= 'F') return h - 'A' + 10;
            Assert.Fail("Invalid hex character " + h);
            return -1;
        }

        public static void AddDependencyPropertyChangeListener(object component, DependencyProperty property, EventHandler listener)
        {
            if (component == null) return;
            Assert.IsNotNull(property);
            Assert.IsNotNull(listener);
            DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(property, component.GetType());
            dpd.AddValueChanged(component, listener);
        }

        public static void RemoveDependencyPropertyChangeListener(object component, DependencyProperty property, EventHandler listener)
        {
            if (component == null) return;
            Assert.IsNotNull(property);
            Assert.IsNotNull(listener);
            DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(property, component.GetType());
            dpd.RemoveValueChanged(component, listener);
        }

        #region Extension Methods

        public static bool IsThicknessNonNegative(Thickness thickness)
        {
            if (!IsDoubleFiniteAndNonNegative(thickness.Top)) return false;
            if (!IsDoubleFiniteAndNonNegative(thickness.Left)) return false;
            if (!IsDoubleFiniteAndNonNegative(thickness.Bottom)) return false;
            if (!IsDoubleFiniteAndNonNegative(thickness.Right)) return false;
            return true;
        }

        public static bool IsCornerRadiusValid(CornerRadius cornerRadius)
        {
            if (!IsDoubleFiniteAndNonNegative(cornerRadius.TopLeft)) return false;
            if (!IsDoubleFiniteAndNonNegative(cornerRadius.TopRight)) return false;
            if (!IsDoubleFiniteAndNonNegative(cornerRadius.BottomLeft)) return false;
            if (!IsDoubleFiniteAndNonNegative(cornerRadius.BottomRight)) return false;
            return true;
        }

        public static bool IsDoubleFiniteAndNonNegative(double d) => !double.IsNaN(d) && !double.IsInfinity(d) && !(d < 0);

        #endregion Extension Methods
    }
}